var a = new Array(n);
a[0] = 2;
ii = 1;
for(i = 3; ii < n; i+=2) {
  tof = Math.sqrt(i);
  test = true;
  for(j = 0; a[j] <= tof; j++)
    if (i % a[j] == 0)
      test = false;
  if (test) {
    a[ii] = i;
    ii++;
  }    
}
alert&#40;a[a.length - 1]&#41;;

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